Liquid level gauges are often used on tanks that contain highly pressurized, flammable fluids such as propane and CFC's. A longstanding problem exists in insuring zero leakage around the threads of the gauge fitting in the tank. One of the main causes of leaking threads is damage to the threads that occurred during assembly, packaging or shipping of the gauge. Leakage of fluids such as liquid petroleum and CFC's is highly dangerous and can result in explosions. Thus, it is extremely important that the gauge threads have no damage so there will be zero leakage around the threads when installed on a high pressure tank.
Liquid level gauges typically include a fitting that is threaded into a hole in a tank wall. The gauge dial is typically disposed on the head of the fitting outside the tank, and the fitting has a passage extending through it. An extension piece of some type is inserted into this passage that extends into the interior of the tank. The extension piece can be a tube or some type of rod. A float mechanism is assembled in conjunction with the extension piece to respond to the liquid level in the tank.
During assembly of the various gauge components to the fitting, the threads of the fitting are susceptible to being damaged by the various components and other gauges on the assembly line. The threads of the fitting are also exposed to damage during packaging, shipping and storage. Such damage to the threads can render the gauge assembly unusable, and, often, thread damage is not detected until the gauge is being installed. At this time, the gauge customer is tremendously inconvenienced by having to order a replacement gauge with undamaged threads.
Conventional thread protectors have been used on the fittings that cover the passage through the fitting. Such thread protectors must be removed before attachment of the extension piece in the fitting. Thus, the threads are still exposed to a risk of damage during the remaining assembly steps as well as packaging and shipping. Therefore, a need exists for a thread protector that can be used on fittings used in gauge assemblies that allows assembly of the gauge components to the fitting without having to remove the thread protector.
Furthermore, a thread protector that allows assembly of the gauge components to the fitting must be readily removable from the fitting when the gauge is ready to be installed on a tank. A sleeve-like thread protector can not be removed over many of the types of float mechanisms which are attached to extension pieces extending from the fittings. Thus, a need exists for a thread protector that not only allows assembly of the extension piece to the fitting but that can then be readily removed from the threads without having to run the protector down over the end of the extension piece and any mechanisms attached to the extension piece.
A need also exists for a pre-installation gauge assembly that provides for protection of the threads of the fitting that is readily removable prior to installation of the gauge assembly. A need also exists for a method of protecting the threads of a gauge fitting during the manufacture, packaging and shipping of the gauge assemblies.
Additionally, a sealant is often used on the threads of the fittings when they are threaded into a hole in a tank wall. A need exists to be able to apply the sealant in the threads of the fitting at the gauge assembly plant without risk of contaminating or disturbing the sealant during assembly, packaging, and shipping. With suitable protection for pre-applied sealant, installation of the gauge assemblies is simplified by eliminating the need to apply sealant at the point of installation.